title: Perceiving nonverbal behavior: neural correlates of processing movement fluency and contingency in dyadic interactions.
abstract: Despite the fact that nonverbal dyadic social interactions are abundant in the environment, the neural mechanisms underlying their processing are not yet fully understood. Research in the field of social neuroscience has suggested that two neural networks appear to be involved in social understanding: (1) the action observation network (AON) and (2) the social neural network (SNN). The aim of this study was to determine the differential contributions of the AON and the SNN to the processing of nonverbal behavior as observed in dyadic social interactions. To this end, we used short computer animation sequences displaying dyadic social interactions between two virtual characters and systematically manipulated two key features of movement activity, which are known to influence the perception of meaning in nonverbal stimuli: (1) movement fluency and (2) contingency of movement patterns. A group of 21 male participants rated the "naturalness" of the observed scenes on a four-point scale while undergoing fMRI. Behavioral results showed that both fluency and contingency significantly influenced the "naturalness" experience of the presented animations. Neurally, the AON was preferentially engaged when processing contingent movement patterns, but did not discriminate between different degrees of movement fluency. In contrast, regions of the SNN were engaged more strongly when observing dyads with disturbed movement fluency. In conclusion, while the AON is involved in the general processing of contingent social actions, irrespective of their kinematic properties, the SNN is preferentially recruited when atypical kinematic properties prompt inferences about the agents' intentions.
authors.affiliation: Neuroimaging Research Group, Department of Psychiatry and Psychotherapy, University Hospital of Cologne, Cologne, Germany.
authors.forename: Alexandra L
authors.initials: AL
authors.lastname: Georgescu
authors.forename: Bojana
authors.initials: B
authors.lastname: Kuzmanovic
authors.forename: Natacha S
authors.initials: NS
authors.lastname: Santos
authors.forename: Ralf
authors.initials: R
authors.lastname: Tepest
authors.forename: Gary
authors.initials: G
authors.lastname: Bente
authors.forename: Marc
authors.initials: M
authors.lastname: Tittgemeyer
authors.forename: Kai
authors.initials: K
authors.lastname: Vogeley
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009039:Motion Perception / Q000502:physiology*; D009043:Motor Activity; D009434:Neural Pathways / Q000502:physiology; D009483:Neuropsychological Tests; D009633:Nonverbal Communication; D010775:Photic Stimulation; D012938:Social Perception; D014741:Video Recording; D055815:Young Adult
keywords: action observation network; dyadic social interaction; fMRI; nonverbal behavior; social neural network